Tangeretin has anti-asthmatic effects via regulating PI3K and Notch signaling and modulating Th1/Th2/Th17 cytokine balance in neonatal asthmatic mice

The impact of tangeretin combined with whey protein on exercise-induced bronchoconstriction in professional athletes: a placebo-controlled trial

BACKGROUND

Exercise-induced bronchoconstriction (EIB) is highly prevalent in athletes. The objective of this study was to assess the therapeutic efficacy of daily tangeretin combined with whey protein supplementation over a period of 4 weeks in professional athletes with EIB.

METHODS

Using a placebo-controlled, double-blind, paired, randomized trial design, a cohort of 30 professional athletes with EIB, consisting of 14 females and 16 males, was divided into two groups: the tangeretin combined with whey protein intervention group (TIG), and the placebo control group (PCG). Both the TIG and PCG underwent exercise challenge tests (ECT) and VO2max tests before (ECT1, V1) and after (ECT2, V2) the intervention. Blood (eosinophils, neutrophils, and basophils) and serum (interleukin-5, IL-5; interleukin-8, IL-8; Clara cell secretory protein-16, CC16; immunoglobulin E, IgE) levels were measured early in the morning of ECT1 and ECT2, respectively. Lung function was assessed immediately before and post-ECT immediately.

RESULTS

Tangeretin combined with whey protein use for 4 weeks attenuated the decrease in forced expiratory volume in 1 s (FEV1) post trials (∆FEV1(ECT1-ECT2): mean (SD) TIG -7.51(6.9)% vs. PCG -2.33(11.49)%, p = 0.013). Tangeretin also substantially attenuated IL-5 concentration (∆IL-5(T1-T5): Tangeretin -19.4% vs Placebo + 8.37%, p = 0.022); IL-8 concentration (∆IL-8(T1-T5): Tangeretin -17.28% vs Placebo + 6.1%, p = 0.012); CC16 concentration (∆CC16(T1-T5): Tangeretin -11.77% vs Placebo + 24.19%); and IgE concentration in the serum (∆IgE(T1-T5): Tangeretin -24.1% vs Placebo -3.9%), and significantly decreased neutrophil count (∆N(T1-T5): Tangeretin -11.34% vs Placebo + 0.3%) and eosinophil count in blood (∆N(T1-T5): Tangeretin -38.5% vs Placebo + 4.35%). Compared with V1, VO2max (p = 0.042) and TLim (p = 0.05) of V2 were significantly increased in the TIG, and there was no significant change in the PCG. Meanwhile, six athletes in the TIG and 0 athletes in the PCG became EIB-negative at ECT2; the overall negative conversion rate of EIB was 40.00% in TCG. Additionally, the number of cough symptoms decreased from 9 to 3 and dyspnea from 4 to 2 in the TIG.

CONCLUSION

After high-intensity exercise, athletes with EIB achieved significant improvements in lung function and blood inflammatory factors by combining tangeretin and whey protein supplementation. EIB athletes also showed longer exercise endurance and VO2max at 4 weeks after TI. In addition, some patient symptoms disappeared after combination supplementation. The effect of this treatment on professional athletes with EIB was beneficial.

Synthesis, characterisation, and in vitro antiparasitic activity of new flavanoidal tetrazinan-6'-ones and their binding study with calf thymus DNA using molecular modelling and spectroscopic techniques

With the developing resistance to traditional antiparasitic medications, the purpose of this study was to efficiently develop a series of six noble flavanoidal tetrazinane-6'-one derivatives by a one-pot reaction pathway. FT-IR, 1HNMR, 13CNMR, and Mass spectra were employed for the structural elucidation of the synthesized compounds (7-12). Clinostomum complanatum, a parasite infection model that has been well-established, demonstrated that all the synthesized compounds are potent antiparasitic agents. DNA is the main target for various medicinal compounds. As a result, thestudy of how small molecules attach to DNA has received a lot of attention. In the present study, we have performed various biophysical techniques to determine the mode of binding of synthesized compounds (7-12) with calf thymus DNA (ct-DNA). It was observed from the UV-visible absorbance and fluorescence spectra that all synthesized compounds (7-12) form complexes with the ct-DNA. The value of binding constant (Kb) was obtained to be in the range of 4.36---24.50 × 103 M - 1 at 298 K. Competitive displacement assay with ethidium bromide (EB), CD spectral analysis, viscosity measurements, and in silico molecular docking confirmed that ligands (7-12) incorporate with ct-DNA through groove binding only. Molecular docking studies were performed for all synthesized compounds with the calf thymus DNA and it was found that all the newly synthesized compounds strongly bind with the chain B of DNA in the minor groove with the value of binding energy in the range of -8.54 to -9.04 kcal per mole and several hydrogen bonding interactions.

Examining the contribution of Notch signaling to lung disease development

Notch pathway is a widely observed signaling system that holds pivotal functions in regulating various developmental cellular functions and operations. The Notch signaling mechanism is crucial for lung homeostasis, damage, and restoration. Based on increasing evidence, the Notch pathway has been identified, as critical for fibrosis and subsequently, the development of chronic fibroproliferative conditions in various organs and tissues. Recent research indicates that deregulation of Notch signaling correlates with the pathogenesis of significant pulmonary conditions, particularly chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, asthma, pulmonary arterial hypertension (PAH), lung carcinoma, and pulmonary abnormalities in some hereditary disorders. In various cellular and tissue environments, and across both physiological and pathological conditions, multiple consequences of Notch activation have been observed. Studies have ascertained that the Notch signaling cascade exhibits close associations with various other signaling systems. This study provides an updated overview of Notch signaling's role, especially its link to fibrosis and its potential therapeutic implications. This study sheds light on the latest findings regarding the mechanisms and outcomes of irregular or lacking Notch activity in the onset and development of pulmonary diseases. As our insight into this signaling mechanism suggests that modulating Notch signaling might hold potential as a valuable additional therapeutic approach in upcoming research.

Se-rich tea polysaccharide extracted by high hydrostatic pressure attenuated anaphylaxis by improving gut microbiota and metabolic regulation

Selenium-rich tea polysaccharides (Se-TPS) were extracted via high hydrostatic pressure technology with a pressure of 400 MPa (200-500 MPa) for 10 min (3-20 min) at a material-to-solvent ratio of 1:40 (1:20-1:50). Subsequently, Se-TPS1-4 were isolated and purified, with Se-TPS3-4 as the main components. A spectral analysis proved that Se, which has antioxidant activity, existed. An in vitro study found that among Se-TPS, Se-TPS3-4 attenuated the release of β-hexosaminidase, histamine, and interleukin (IL)-4. Furthermore, in vivo experiments revealed that treatment with Se-TPS downregulated IL-4 levels and upregulated TGF-β and interferon-γ levels to improve imbalanced Th1/Th2 immunity in tropomyosin-sensitized mice. Moreover, Se-TPS promoted Lactobacillus and norank_f_Muribaculaceaek growth and upregulated metabolites such as genipin and coniferyl alcohol. Overall, these results showed the strong anti-allergy potential of Se-TPS by regulating mast cell-mediated allergic inflammatory responses and microbiota regulation, highlighting the potential of Se-TPS as a novel therapeutic agent to regulate allergy-associated metabolic disorders.

Myeloid-specific knockout of Notch-1 inhibits MyD88- and TRIF-mediated TLR signaling pathways by regulating oxidative stress-SHP2 axis, thus restraining aneurysm progression

OBJECTIVE

Notch-1 is a signal regulatory protein with extensive effects in myeloid cells, but its role in aneurysms remains to be fully clarified. In this study, therefore, the aneurysm mouse model with myeloid-specific knockout of Notch-1 was established to observe the role of Notch-1 in aneurysm progression.

METHODS AND RESULTS

The effect of Notch-1 was assessed by pathological staining and Western blotting. It was found that after myeloid-specific knockout of Notch-1 in the aneurysm mouse model, the area of aneurysms and the macrophage infiltration were significantly reduced, the damage to arterial elastic plates was significantly relieved, and the oxidative stress level significantly declined. The results of Western blotting showed that after myeloid-specific knockout of Notch-1, the levels of oxidative stress-related proteins p22 and p47 in aneurysm tissues significantly declined, accompanied by a significant increase in the protein level of Src homology 2 domain-containing tyrosine phosphatase-2 (SHP2). In addition, the levels of phosphorylated myeloid differential protein-88 (MyD88), TIR domain-containing adaptor-inducing interferon-β (TRIF) and nuclear factor-κB (NF-κB), and inflammatory cytokines interferon-γ (IFN-γ), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) also significantly decreased after myeloid-specific knockout of Notch-1. Following myeloid-specific knockout of Notch-1, the phagocytic capacity of macrophages was enhanced by promoting the SHP2 signaling pathway.

CONCLUSION

Notch-1 in monocytes/macrophages can activate the Toll-like receptor (TLR)-mediated inflammatory and stress responses by activating oxidative stress and inhibiting the SHP2 protein expression, thus facilitating aneurysm progression.

Phytochemicals as treatment for allergic asthma: Therapeutic effects and mechanisms of action

BACKGROUND

Allergic asthma is an inflammatory disease caused by the immune system's reaction to allergens, inflammation and narrowing of the airways, and the production of more than normal mucus. One of the main reasons is an increased production of inflammatory cytokines in the lungs that leads to the appearance of symptoms of asthma, including inflammation and shortness of breath. On the other hand, it has been proven that phytochemicals with their antioxidant and anti-inflammatory properties can be useful in improving allergic asthma.

PURPOSE

Common chemical treatments for allergic asthma include corticosteroids, which have many side effects and temporarily relieve symptoms but are not a cure. Therefore, taking the help of natural compounds to improve the quality of life of asthmatic patients can be a valuable issue that has been evaluated in the present review.

STUDY DESIGN AND METHODS

In this study, three databases (Scopus, PubMed, and Cochrane) with the keywords: allergic asthma, phytochemical, plant, and herb were evaluated. The primary result was 5307 articles. Non-English, repetitive, and review articles were deleted from the study.

RESULTS AND DISCUSSION

Finally, after carefully reading the articles, 102 were included in the study (2006-2022). The results of this review state that phytochemicals suppress the inflammatory pathways via inhibition of inflammatory cytokines production/secretion, genes, and proteins involved in the inflammation process, reducing oxidative stress indicators and symptoms of allergic asthma, such as cough and mucus production in the lungs.

CONCLUSION

With their antioxidant effects, this study concluded that phytochemicals suppress cytokines and other inflammatory indicators and thus can be considered an adjunctive treatment for improving allergic asthma.

Mechanistic analysis of Th2-type inflammatory factors in asthma

Background

The main pathological features of asthma are widespread chronic inflammation of the airways and restricted ventilation due to airway remodeling, which involves changes in a range of regulatory pathways. While the role of T helper type 2 (Th2)-related inflammatory factors in this process is known, the detailed understanding of how genes affect protein functions during airway remodeling is still lacking. This study aims to fill this knowledge gap by integrating gene expression data and protein function analysis, providing new scientific insights for a deeper understanding of the mechanisms of airway remodeling and for further development of asthma treatment strategies.

Methods

In this study, the mechanism of Th2-related inflammatory factors in tracheal remodeling was studied through differentially expressed gene (DEG) screening, enrichment analysis, protein-protein interaction (PPI) network construction, machine learning, and the construction of a line graph model.

Results

Our study revealed that S100A14, KRT6A, S100A2, ABCA13, UBE2C, RASSF10, PSCA, PLAT, and TIMP1 may be the key genes for airway remodeling; epithelial-mesenchymal transition (EMT)-related genes GEM, TPM4, SLC6A8, and SNTB1 may be involved in airway remodeling due to asthma; IL6 may affect the occurrence of airway remodeling by binding to UBE2C protein or by regulating GEM genes, respectively; IL6 and IL9 may affect the occurrence of airway remodeling by regulating the downstream Toll-like receptor (TLR) signaling pathway and thus IL6 and IL9 may influence the occurrence of tracheal remodeling by regulating downstream TLR signaling pathways.

Conclusions

This study further mined the asthma gene microarray database through bioinformatics analysis and identified key genes and important pathways affecting airway remodeling in asthma patients, providing new ideas to uncover the mechanism of airway remodeling due to asthma and then seek new therapeutic targets.

Kindlin-2 in myoepithelium controls luminal progenitor commitment to alveoli in mouse mammary gland

Myoepithelium plays an important role in mammary gland development, but less is known about the molecular mechanism underlying how myoepithelium controls acinus differentiation during gestation. Herein, we found that loss of Kindlin-2 in myoepithelial cells impaired mammary morphogenesis, alveologenesis, and lactation. Using five genetically modified mouse lines combined with single-cell RNA sequencing, we found a Kindlin-2-Stat3-Dll1 signaling cascade in myoepithelial cells that inactivates Notch signaling in luminal cells and consequently drives luminal progenitor commitment to alveolar cells identity. Single-cell profiling revealed that Kindlin-2 loss significantly reduces the proportion of matured alveolar cells. Mechanistically, Kindlin-2 depletion in myoepithelial cells promotes Stat3 activation and upregulates Dll1, which activates the Notch pathway in luminal cells and inhibits luminal progenitor differentiation and maturation during gestation. Inhibition of Notch1 with tangeretin allowed luminal progenitors to regain commitment ability in the pregnant mice with Kindlin-2 depletion in myoepithelium. Taken together, we demonstrated that Kindlin-2 is essential to myoepithelium-controlled luminal progenitors to alveoli transition during gestation.

DMBT1 Alleviates Nasal Airway Inflammatory Response in the LPS-Induced Nasal Polyp Model

INTRODUCTION

The aim of this study was to investigate the effects and mechanism of deleted in malignant brain tumors 1 (DMBT1) protein on the mouse model of nasal polyps.

METHODS

The mouse model of nasal polyps was induced by intranasal drip intervention of lipopolysaccharide (LPS) 3 times a week for 12 weeks. A total of 42 mice were randomly divided into blank group, LPS group, and LPS+DMBT1 group. DMBT1 protein was applied by intranasal drip intervention in each nostril after LPS. After 12 weeks, 5 mice in each group were randomly picked for the mouse olfactory disorder experiment, 3 mice were randomly picked for histopathological observation of nasal mucosa, 3 mice for olfactory marker protein (OMP) immunofluorescence analysis and the last 3 mice were grabbed for nasal lavage, and the levels of cytokines interleukin (IL)-4, IL-5, IL-13, and phosphatidylinositide 3-kinases (PI3K) in the nasal lavage fluid were detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared with the blank group, mice in LPS group had olfactory dysfunction, the level of OMP was significantly reduced, the nasal mucosa was swollen, discontinuous, and contained a large number of inflammatory cells. The levels of IL-4, IL-5, IL-13, and PI3K in the nasal lavage fluid were significantly increased in LPS group (p < 0.01). Compared with the LPS group, the number of mice with olfactory dysfunction in the LPS+DMBT1 group was less, the infiltration of inflammatory cells was reduced, the OMP-positive cells were significantly increased, and the IL-4, IL-5, IL-13, and PI3K in the nasal lavage fluid were significantly increased, p < 0.01.

CONCLUSIONS

DMBT1 protein alleviates the nasal airway inflammatory response in the mouse nasal polyp model, and the mechanism may be through the PI3K-AKT signaling pathway.

Exploring Pro-Inflammatory Immunological Mediators: Unraveling the Mechanisms of Neuroinflammation in Lysosomal Storage Diseases

Lysosomal storage diseases are a group of rare and ultra-rare genetic disorders caused by defects in specific genes that result in the accumulation of toxic substances in the lysosome. This excess accumulation of such cellular materials stimulates the activation of immune and neurological cells, leading to neuroinflammation and neurodegeneration in the central and peripheral nervous systems. Examples of lysosomal storage diseases include Gaucher, Fabry, Tay–Sachs, Sandhoff, and Wolman diseases. These diseases are characterized by the accumulation of various substrates, such as glucosylceramide, globotriaosylceramide, ganglioside GM2, sphingomyelin, ceramide, and triglycerides, in the affected cells. The resulting pro-inflammatory environment leads to the generation of pro-inflammatory cytokines, chemokines, growth factors, and several components of complement cascades, which contribute to the progressive neurodegeneration seen in these diseases. In this study, we provide an overview of the genetic defects associated with lysosomal storage diseases and their impact on the induction of neuro-immune inflammation. By understanding the underlying mechanisms behind these diseases, we aim to provide new insights into potential biomarkers and therapeutic targets for monitoring and managing the severity of these diseases. In conclusion, lysosomal storage diseases present a complex challenge for patients and clinicians, but this study offers a comprehensive overview of the impact of these diseases on the central and peripheral nervous systems and provides a foundation for further research into potential treatments.

Aqueous Extract from Cuminum cyminum L. Seed Alleviates Ovalbumin-Induced Allergic Rhinitis in Mouse via Balancing of Helper T Cells

Cuminum cyminum L. (cumin) seeds are widely used as a spice. Although we previously reported that the aqueous extract of cumin seeds suppresses the degranulation of rat basophilic RBL-2H3 cells, it has not been clarified whether the extract alleviates actual allergy symptoms in vivo. Therefore, in this study, we investigated the effect of oral administration of cumin seed aqueous extract (CAE) in ovalbumin (OVA)-induced allergic rhinitis. BALB/c mice were randomly divided into the following three groups: control group (five mice), OVA group (five mice), and OVA + CAE group (five mice). Allergic rhinitis was induced by sensitization (intraperitoneal, 25 μg OVA and 1.98 mg aluminum hydroxide gel) followed by challenge (intranasal, 400 μg OVA). The oral administration of CAE (25 mg/kg) reduced the sneezing frequency of OVA-induced allergic rhinitis model mice. In addition to reducing the serum immunoglobulin E and IL-4 levels, the oral administration of CAE reduced the production of T-helper type-2 (Th2) cytokines (IL-4, IL-5, IL-10, and IL-13) in the splenocytes of the model mice. Furthermore, a significant increase in the ratio of Th1 to Th2 cells was observed in the CAE-administered group. Our findings suggest that the ingestion of CAE improves T cell balance, the dominant state of Th2, and alleviates allergic rhinitis symptoms.

Identifying Active Compounds and Mechanisms of Citrus changshan-Huyou Y. B. Chang against URTIs-Associated Inflammation by Network Pharmacology in Combination with Molecular Docking

Purpose. The ripe fruits of Citrus changshan-huyou, known as Quzhou Fructus Aurantii (QFA), have been commonly used for respiratory diseases. The purpose of this study was to investigate their active compounds and demonstrate their mechanism in the treatment of upper respiratory tract infections (URTIs) through network pharmacology and molecular docking. Methods. The prominent compounds of QFA were acquired from TCMSP database. Their targets were retrieved from SwissTargetPrediction database, and target genes associated with URTIs were collected from DisGeNET and GeneCards databases. The target protein-protein interaction (PPI) network was constructed by using STRING database and Cytoscape. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were enriched. Visual compound-target-pathway network was established with Cytoscape. The effects of compounds were verified on the inhibitory activities against phosphoinositide 3-kinases (PI3Ks). Finally, the molecular docking was carried out to confirm the binding affinity of the bioactive compounds and target proteins. Results. Five important active compounds, naringenin (NAR), tangeretin (TAN), luteolin (LUT), hesperetin (HES), and auraptene (AUR), were obtained. The enrichment analysis demonstrated that the pathways associated with inflammation mainly contained PI3K/Akt signalling pathway, TNF signalling pathway, and so on. The most important targets covering inflammation-related proteins might be PI3Ks. In vitro assays and molecular docking exhibited that TAN, LUT, and AUR acted as PI3Kγ inhibitors. Conclusion. The results revealed that QFA could treat URTIs through a multi-compound, multi-target, multi-pathway network, in which TAN, LUT, and AUR acted as PI3Kγ inhibitors, probably contributing to a crucial role in treatment of URTIs.

Mechanism of Action of Yin Nourishing and Heat Clearing Prescription in Treating Cough Variant Asthma Based on Network Pharmacology and Molecular Docking Verification

Objective. To explore the mechanism of action of the yin nourishing and heat clearing prescription in treating cough variant asthma (CVA) based on network pharmacology (NP). Methods. The active ingredients and targets of the yin nourishing and heat clearing prescription were screened using the Traditional Chinese Medicine System Pharmacology Analysis Platform (TCMSP); CVA targets were screened by the GeneCards, NCBI gene, and OMIM databases to construct the component-target network and the protein-protein interaction (PPI) network. GO functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the target genes were performed to construct the component-disease-pathway-target biological network. Moreover, CVA-related core target structures with high values were subjected to molecular docking (MD) with the active components. Results. We found 265 eligible targets in the prescription and 1115 CVA-related genes. The medicine targets were intersected with disease targets, which yielded 148 common targets. After topology analysis, 66 key targets were screened. Upon GO functional annotation, 2408 biological processes, 153 molecular functions, and 162 KEGG pathways were enriched. Molecular docking results suggested that the major active ingredients of the prescription showed high affinity to the key targets, among which AKT1 might be the most important target. Conclusions. Active ingredients might act on AKT1, IL-6, VEGFA, IL-1B, and JUN to suppress eosinophil accumulation, decrease histamine release, suppress airway inflammation, regulate the airway immune microenvironment, increase autophagy in lung tissue, inhibit mucus production, and reduce airway resistance and hyperresponsiveness, thus treating CVA. Our findings provide a reference for further research and clinical applications of the prescription.

Effects of 4-Week Tangeretin Supplementation on Cortisol Stress Response Induced by High-Intensity Resistance Exercise: A Randomized Controlled Trial

Objective: This study aimed to investigate the effects of 4-week tangeretin supplementation on the cortisol stress response induced by high-intensity resistance exercise.

Methods: A randomized controlled trial of twenty-four soccer players was conducted during the winter training season. The experimental group (EG) took the oral supplement with tangeretin (200 mg/day) and the control group (CG) took placebo for 4 weeks. Before and after the 4-week intervention, all players performed a high intensity bout of resistance exercise to stimulate their cortisol stress responses. Serum cortisol, adreno-corticotropic hormone (ACTH) and superoxide dismutase (SOD) were obtained by collecting blood samples before (PRE), immediately after (P0), and 10 (P10), 20 (P20) and 30 minutes (P30) after the exercise.

Results: The serum cortisol level (PRE, p = 0.017; P10, p = 0.010; P20, p = 0.014; P30, p = 0.007) and ACTH (P10, p = 0.037; P30, p = 0.049) of experimental group significantly decreased after the 4-week intervention. Compared with control group, EG displayed a significantly lower level of the serum cortisol (PRE, p = 0.036; P10, p = 0.031) and ACTH (P30, p = 0.044). Additionally, EG presented significantly higher superoxide dismutase activity level compared with CG at P30 (p = 0.044). The white blood cell of EG decreased significantly (PRE, p = 0.037; P30, p = 0.046) and was significantly lower than CG at P20 (p = 0.01) and P30 (p = 0.003).

Conclusion: Four-week tangeretin supplementation can reduce serum cortisol and ACTH, which may ameliorate the cortisol stress response in soccer players during high-intensity resistance exercise training. It can also enhance antioxidant capacity, accelerate the elimination of inflammation throughout the body, and shorten recovery time after high-intensity exercise.

Influence of Tangeretin on the Exponential Regression of Inflammation and Oxidative Stress in Streptozotocin-Induced Diabetic Nephropathy

Diabetes is an amalgamation of metabolic disorders marked by hyperglycemia. Over time diabetes brings up several other complications with it like cardiovascular disease, retinopathy, neuropathy, and nephropathy. among which diabetic nephropathy (DN) is the one we are concerned about in the present study. Diabetes management requires following a healthy lifestyle with proper medication. Most of the anti-diabetic drugs available at present come with adverse side effects. Nature has provided us with several components that are anti-diabetic in nature which has fewer or no side effects and tangeretin is one among them. Tangeretin is a natural flavonoid abundantly present in orange peel and tangerines. Our study is designed to evaluate tangeretin, as an anti-diabetic medication especially for patients suffering from diabetic nephropathy. The procured healthy rats were first divided into four groups: the group I was maintained as healthy control and the others were subjected to the induction of diabetes by i.p. injection of streptozotocin (STZ) at the concentration of 55mg/kg b.wt .Then, the diabetic rats were further divided into three groups: group II was used as the diabetic control rats and the group III and group IV were administered with tangeretin (25mg/kg b.wt) and positive control drug metformin (150mg/kg b.wt) for 8 weeks. The body weight, blood glucose, and serum insulin levels were estimated at week 0 and week 8. Reactive oxygen species (ROS) inhibitory effect, antioxidant, antilipidemic, nephroprotective, and anti-inflammatory effects of tangeretin on the diabetic-induced rats were evaluated at the end of week 8 in addition to the histopathological assessment of the sections of the kidneys of the experimental rats. All the test results concluded that tangeretin was able to significantly decelerate the progression of DN in STZ-induced diabetic rats.

Polyphenols affect the humoral response in cancer, infectious and allergic diseases and autoimmunity by modulating the activity of TH1 and TH2 cells

Polyphenols are a wide class of natural substances, pleiotropic molecules capable of modulating several processes, involved in the humoral and cellular immune response. The activation, differentiation of B cells, and production of antibodies to protein antigens by plasma cells depend on T helper (T_H) CD4⁺ cells and secreted cytokines. Cancer, infectious, allergic, and autoimmune diseases are characterized by an imbalance of T_H1/T_H2 immunity and abnormal activation of the humoral response. Accordingly, polyphenols modulate the T_H1/T_H2 ratio, the secretion of multiple cytokines, the levels of antibodies, and therefore could contribute to recovering the state of health in these diseases. In this review, we summarize the current knowledge on the effects of polyphenols in modulating the humoral response in cancer, infectious and allergic diseases and in autoimmunity by affecting the activity of T_H1 and T_H2 cells.

Integrative Bioinformatics Study of Tangeretin Potential Targets for Preventing Metastatic Breast Cancer

Agents that target metastasis are important to improve treatment efficacy in patients with breast cancer. Tangeretin, a citrus flavonoid, exhibits antimetastatic effects on breast cancer cells, but its molecular mechanism remains unclear. Tangeretin targets were retrieved from PubChem, whereas metastatic breast cancer regulatory genes were downloaded from PubMed. In total, 58 genes were identified as potential therapeutic target genes of tangeretin (PTs). GO and KEGG pathway enrichment analyses of PTs were performed using WebGestalt (WEB-based Gene SeT AnaLysis Toolkit). The PPI network was analyzed using STRING-DB v11.0 and visualized by Cytoscape software. Hub genes were selected on the basis of the highest degree score as calculated by the CytoHubba plugin. Genetic alterations of the PTs were analyzed using cBioPortal. The prognostic values of the PTs were evaluated with the Kaplan-Meier plot. The expression of PTs across breast cancer samples was confirmed using GEPIA. The reliability of the PTs in metastatic breast cancer cells was validated using ONCOMINE. Molecular docking was performed to foresee the binding sites of tangeretin with PIK3Cα, MMP9, PTGS2, COX-2, and IKK. GO analysis showed that PTs participate in the biological process of stimulus response, are the cellular components of the nucleus and the membrane, and play molecular roles in enzyme regulation. KEGG pathway enrichment analysis revealed that PTs regulate the PI3K/Akt pathway. Genetic alterations for each target gene were MTOR (3%), NOTCH1 (4%), TP53 (42%), MMP9 (4%), NFKB1 (3%), PIK3CA (32%), PTGS2 (15%), and RELA (5%). The Kaplan-Meier plot showed that patients with low mRNA expression levels of MTOR, TP53, MMP9, NFKB1, PTGS2, and RELA and high expression of PIK3CA had a significantly better prognosis than their counterparts. Further validation of gene expression by using GEPIA revealed that the mRNA expression of MMP9 was significantly higher in breast cancer tissues than in normal tissues, whereas the mRNA expression of PTGS2 showed the opposite. Analysis with ONCOMINE demonstrated that the mRNA expression levels of MMP9 and NFKB1 were significantly higher in metastatic breast cancer cells than in normal tissues. The results of molecular docking analyses revealed the advantage of tangeretin as an inhibitor of PIK3CA, MMP9, PTGS2, and IKK. Tangeretin inhibits metastasis in breast cancer cells by targeting TP53, PTGS2, MMP9, and PIK3CA and regulating the PI3K/Akt signaling pathway. Further investigation is needed to validate the results of this study.

Selective activation of cannabinoid receptor 2 regulates Treg/Th17 balance to ameliorate neutrophilic asthma in mice

Background

The cannabinoid receptor 2 (CNR2) plays a critical role in relieving asthma, with the mechanism still unclear. We aimed to investigate the mechanism of the CNR2 agonist (β-caryophyllene, β-Car) in regulating the balance of regulatory T cells (Treg) and T helper cell 17 (Th17) and thus its role in asthma.

Methods

The study group of 50 pathogen-free female BALB/c mice were randomly divided at 6–8 weeks old into five groups of Control, Asthma, Asthma + β-Car (10 mg/kg), Asthma + β-Car + SR144528 (specific CNR2 antagonist, 3 mg/kg), and Asthma + β-Car + CMD178 (inhibitor of Treg cell, 10 mg/kg). ELISA was conducted to evaluate the main inflammatory cytokines [interleukin (IL)-6, IL-8, and tumor necrosis factor-α], and those secreted by Treg (transforming growth factor-β and IL-10), and Th17 (IL-17A and IL-22). Markers of Treg and Th17 cells were assessed by flow cytometry. In vitro, the CD4⁺ T cells were sorted and directed to differentiate to Treg and Th17 cells. The expression levels of CNR2, STAT5 and JNK1/2 were investigated by western blot and immunofluorescence assay.

Results

β-Car relieved neutrophilic asthma severity in mice by elevating the marker genes’ expression of Treg and inhibiting those of Th17, causing an increased proportion of Treg to Th17. β-Car also promoted the directed differentiation of CD4⁺ T cells into Treg, but not Th17. Activation of the CNR2 regulated the Treg/Th17 balance and relieved neutrophilic asthma possibly through promotion of phosphorylation of STAT5 and JNK1/2.

Conclusions

The effect of the selective CNR2 agonist activating STAT5 and JNK1/2 signaling was to change the Treg/Th17 balance and reduce the inflammatory reaction, thus ameliorating neutrophilic asthma in a mouse model.

An Up-to-Date Review on Citrus Flavonoids: Chemistry and Benefits in Health and Diseases

Flavonoids, the main class of polyphenols, are characterized by the presence of 2-phenyl-benzo-pyrane nucleus. They are found in rich quantities in citrus fruits. Citrus flavonoids are classified into flavanones, flavones, flavonols, polymethoxyflavones and anthocyanins (found only in blood oranges). Flavanones are the most abundant flavonoids in citrus fruits. In many situations, there are structure-function relationships. Due to their especial structures and presence of many hydroxyls, polymethoxies and glycoside moiety, the flavonoids have an array of multiple biological and pharmacological activities. This article provides an updated overview of the differences in chemical structures of the classes and members of citrus flavonoids and their benefits in health and diseases. The review article also sheds light on the mechanisms of actions of citrus flavonoids in the treatment of different diseases, including arthritis, diabetes mellitus, cancer and neurodegenerative disorders as well as liver, kidney and heart diseases. The accumulated and updated knowledge in this review may provide useful information and ideas in the discovery of new strategies for the use of citrus flavonoids in the protection, prevention and therapy of diseases.

Therapeutic Implications of a Polymethoxylated Flavone, Tangeretin, in the Management of Cancer via Modulation of Different Molecular Pathways

Chemotherapeutics can induce oxidative stress, inflammation, apoptosis, mitochondrial dysfunction, and abnormalities in neurotransmitter metabolism leading to toxicity. Because there have been no therapeutic strategies developed to target inflammation and oxidative stress, there is a continuing need for new and improved therapy. As a result, there has been increasing interest in complementary and alternative medicine with anticancer potential. Studies have shown that the antioxidant activities and anti-inflammatory effects of citrus fruits are promising natural phytochemicals in the development of new anticancer agents. Tangeretin is a naturally polymethoxylated flavone compound extracted from the citrus peel that has shown significant intestinal absorption and adequate bioavailability, with the added benefit of promoting longevity. In addition, tangeretin is known to exhibit considerable selective toxicity to many types of cancer cell proliferation such as ovarian, brain, blood, and skin cancer. Evidence indicates that tangeretin acts through several mechanisms including growth inhibition, induction of apoptosis, autophagy, antiangiogenesis, and estrogenic-like effects. Furthermore, tangeretin works through mitigating levels of inflammatory mediators in the immune system. Using tangeretin in combination with clinically applied anticancer drugs could be a good strategy for increasing the efficiency of these agents and protecting noncancerous cells from damage caused by chemotherapy. The purpose of this review is to highlight the protective effects of a novel natural product, tangeretin against chemotherapeutic-induced toxicity. The development of chemoprevention strategies can lead to significant health care improvement in cancer survivors. Thus, study outcomes may attract more investigators to conduct tangeretin-related research and find out potentially significant impacts on health care of cancer patients and decreased health problems associated with chemotherapeutics-induced toxicity.

SerpinA3n affects ovalbumin (OVA)-induced asthma in neonatal mice via the regulation of collagen deposition and inflammatory response

OBJECTIVE

To investigate the effects of serine protease inhibitor 3n (SerpinA3n) in a neonatal mouse model of asthma.

METHODS

The study utilized a neonatal mouse ovalbumin (OVA) sensitization model of asthma. Wild type (WT) and SerpinA3n^-/- mice were randomly divided into WT/SerpinA3n^-/- + saline, WT/SerpinA3n^-/- + OVA, WT/SerpinA3n^-/- + OVA + rSerpinA3n (recombinant mouse SerpinA3n protein), and WT/SerpinA3n^-/- + OVA + DEX (dexamethasone, positive control) groups followed by hematoxylin-eosin (HE) staining, Masson's trichrome stainings, Sircol soluble collagen assay, quantitative real time polymerase chain reaction (qRT-PCR), Western Blot and enzyme linked immunosorbent assay (ELISA).

RESULTS

OVA-induced neonatal mice showed the increases in airway hyper-reactivity with the up-regulated total cells, eosinophil, lymphocyte and neutrophil in bronchoalveolar lavage fluid (BALF), which was much higher in WT + OVA + rSerpinA3n group (P < 0.05). SerpinA3n^-/- suppressed the serum concentrations of total immunoglobulin E (IgE) and OVA-specific IgG1 in OVA-induced asthmatic mice, and alleviated the pathological changes of lung tissues, which was reversed by rSerpinA3n injection (P < 0.05). Besides, WT + OVA group showed more severe in collagen deposition in lung tissues than SerpinA3n^-/- + OVA group with increased expression of matrix metallopeptidase-2 (MMP-2), MMP-9, Eotaxin-1, Interleukin 5 (IL-5), IL-13 and IL-4 in lung tissues and deceased IL-10 and Interferon-gamma (IFN-γ) (P < 0.05). Nevertheless, the ameliorating effects of SerpinA3n knockout on OVA-induced asthmatic mice can be reversed by rSerpinA3n.

CONCLUSION

SerpinA3n knockout can attenuate airway hyper-reactivity, mitigate inflammatory responses and reduce collagen deposition in lung tissues of neonatal mice with asthma.

Regulation of γδT17 cells by Mycobacterium vaccae through interference with Notch/Jagged1 signaling pathway

The objective of this study was to investigate the effect of Mycobacterium vaccae on Jagged 1 and gamma delta T17 (γδT17) cells in asthmatic mice. An asthma mouse model was established through immunization with ovalbumin (OVA). Gamma-secretase inhibitor (DAPT) was used to block the Notch signaling pathway. M. vaccae was used to treat asthma, and related indicators were measured. Blocking Notch signaling inhibited the production of γδT17 cells and secretion of cytokine interleukin (IL)-17, which was accompanied by a decrease in Jagged1 mRNA and protein expression in the treated asthma group compared with the untreated asthma group. Similarly, treatment with M. vaccae inhibited Jagged1 expression and γδT17 cell production, which was associated with decreased airway inflammation and reactivity. The Notch signaling pathway may play a role in the pathogenesis of asthma through the induction of Jagged1 receptor. On the other hand, the inhibitory effect of M. vaccae on Jagged1 receptor in γδT17 cells could be used for the prevention and treatment of asthma.

In vivo and in vitro safety evaluation of fermented Citrus sunki peel extract: acute and 90-day repeated oral toxicity studies with genotoxicity assessment

Background

Citrus sunki Hort. ex Tanaka peel has been traditionally used as an ingredient in folk medicine due to its therapeutic effects on promotion of splenic health and diuresis as well as relief of gastrointestinal symptoms. Although a growing interest in health-promoting natural products and the development of highly concentrated products have facilitated consumption of C. sunki peel, its safety assessment has not been explored, posing a potential health risk. In this study, we carried out a series of systemic and genetic toxicity tests on fermented C. sunki peel extract (FCPE) to provide the essential information required for safe use in human.

Methods

We conducted acute and 90-day repeated oral toxicity studies in Sprague-Dawley rats to evaluate systemic toxicity, and three genotoxicity assays to measure bacterial mutation reversion, cellular chromosome aberration and in vivo micronucleus formation.

Results

Single oral administration of FCPE did not cause any clinical signs and lethality in all animals, establishing LD50 to be over 2000 mg/kg BW. Repeated administration of up to 2000 mg/kg BW FCPE for 90 days revealed no test substance-related toxicity as demonstrated in analysis of body weight gain, food/water intake, blood, serum biochemistry, organ weight and histopathology, collectively determining that the no-observable-adverse-effect-level of FCPE is over 2000 mg/kg BW. In addition, we detected no mutagenicity and clastogenicity in FCPE at 5000 μg/plate for the in vitro assays and 2000 mg/kg BW for the in vivo micronucleus test.

Conclusion

FCPE did not cause systemic and genetic toxicity in our model systems at the tested dose levels. These results suggest a guideline for safe consumption of C. sunki peel in human.

Up-regulation of miR-297 mediates aluminum oxide nanoparticle-induced lung inflammation through activation of Notch pathway

Exposure to Aluminum oxide nanoparticles (Al₂O₃ NPs) has been associated with pulmonary inflammation in recent years; however, the underlying mechanism that causes adverse effects remains unclear. In the present study, we characterized microRNA (miRNA) expression profiling in human bronchial epithelial (HBE) cells exposed to Al₂O₃ NPs by miRNA microarray. Among the differentially expressed miRNAs, miR-297, a homologous miRNA in Homo sapiens and Mus musculus, was significantly up-regulated following exposure to Al₂O₃ NPs, compared with that in control. On combined bioinformatic analysis, proteomics analysis, and mRNA microarray, NF-κB-activating protein (NKAP) was found to be a target gene of miR-297 and it was significantly down-regulated in Al₂O₃ NPs-exposed HBE cells and murine lungs, compared with that in control. Meanwhile, inflammatory cytokines, including IL-1β and TNF-α, were significantly increased in bronchoalveolar lavage fluid (BALF) from mice exposed to Al₂O₃ NPs. Then we set up a mouse model with intranasal instillation of antagomiR-297 to further confirm that inhibition of miR-297 expression can rescue pulmonary inflammation via Notch pathway suppression. Collectively, our findings suggested that up-regulation of miR-297 expression was an upstream driver of Notch pathway activation, which might be the underlying mechanism involved in lung inflammation induced by exposure to Al₂O₃ NPs.

Tangeretin Inhibition of High-Glucose-Induced IL-1β, IL-6, TGF-β1, and VEGF Expression in Human RPE Cells

Tangeretin, a natural compound extracted from citrus plants, has been reported to have antiproliferative, antidiabetic, anti-invasive, and antioxidant properties. However, the role of tangeretin in diabetic retinopathy (DR) is unknown. In the present study, we investigated whether tangeretin had any effect on the expression of interleukin 1 beta (IL-1β), interleukin 6 (IL-6), transforming growth factor beta 1 (TGF-β1), and vascular endothelial growth factor (VEGF) in human retinal pigment epithelial (RPE) cells under high-glucose (HG) conditions. Our results illustrated that HG levels induced IL-1β, IL-6, TGF-β1, and VEGF expression and that tangeretin significantly reduced HG-induced IL-1β, IL-6, TGF-β1, and VEGF expression in human RPE cells. Moreover, tangeretin efficiently inhibited the activation of the protein kinase B (Akt) signalling pathway in HG-stimulated RPE cells. Therefore, tangeretin may serve a role in the treatment of DR.

Tangeretin attenuates lipopolysaccharide-induced acute lung injury through Notch signaling pathway via suppressing Th17 cell response in mice

Tangeretin, a polymethoxylated flavonoid is abundant in citrus fruits, which has been reported to inhibit inflammation by inhibiting NF-κB activation and proinflammatory cytokines. Notch blockage inhibits Th17 cells response that are involved in the development of acute lung injury (ALI). This study investigated the protective effects of tangeretin on LPS-induced ALI in mice. Male C57BL/6 mice were treated with phosphate-buffered saline (PBS), lipopolysaccharide (LPS), LPS and tangeretin, or LPS and N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT, a Notch signaling inhibitor), which were harvested at 48 h after challenged by LPS. CD4⁺ T cells were treated with tangeretin or DAPT and harvested after 72 h. Tangeretin notably attenuated pathological changes and decreased the wet to dry weight ratio of the mouse lungs. The total cell and neutrophil counts, tumor necrosis factor (TNF)-α in bronchoalveolar lavage fluid (BALF), myeloperoxidase activity of lung tissue were markedly reduced by tangeretin. The percentage of CD4+IL-17 + T cells in the lungs and the concentration of interleukin (IL)-17 and IL-22 in BALF were significantly down-regulated by tangeretin. As with the positive control (DAPT), tangeretin inhibited the activity of the Notch signaling pathway accompanied with the down-regulation of acid-related orphan receptor gamma t and IL-23 receptor expression. This study demonstrated that tangeretin protects against LPS-induced ALI by suppressing Th17 response at least partially, through a Notch-dependent mechanism.

Advanced Molecular Knowledge of Therapeutic Drugs and Natural Products Focusing on Inflammatory Cytokines in Asthma

Asthma is a common respiratory disease worldwide. Cytokines play a crucial role in the immune system and the inflammatory response to asthma. Abnormal cytokine expression may lead to the development of asthma, which may contribute to pathologies of this disease. As cytokines exhibit pleiotropy and redundancy characteristics, we summarized them according to their biologic activity in asthma development. We classified cytokines in three stages as follows: Group 1 cytokines for the epithelial environment stage, Group 2 cytokines for the Th2 polarization stage, and Group 3 cytokines for the tissue damage stage. The recent cytokine-targeting therapy for clinical use (anti-cytokine antibody/anti-cytokine receptor antibody) and traditional medicinal herbs (pure compounds, single herb, or natural formula) have been discussed in this review. Studies of the Group 2 anti-cytokine/anti-cytokine receptor therapies are more prominent than the studies of the other two groups. Anti-cytokine antibodies/anti-cytokine receptor antibodies for clinical use can be applied for patients who did not respond to standard treatments. For traditional medicinal herbs, anti-asthmatic bioactive compounds derived from medicinal herbs can be divided into five classes: alkaloids, flavonoids, glycosides, polyphenols, and terpenoids. However, the exact pathways targeted by these natural compounds need to be clarified. Using relevant knowledge to develop more comprehensive strategies may provide appropriate treatment for patients with asthma in the future.

Tangeretin inhibits hepatocellular carcinoma proliferation and migration by promoting autophagy-related BECLIN1

Background: Hepatocellular carcinoma (HCC) is a particularly prevalent type of liver cancer and is one of the deadliest malignancies in Asia. Tangeretin is a biological compound extracted from traditional Chinese herbs and has been shown to have potential antitumour properties; however, its mechanism remains largely unknown. Therefore, we sought to determine the role of Tangeretin in HepG2 cells subjected to antitumour treatment. Materials and methods: Cell proliferation was quantified using CCK-8, EdU and colony formation assays, and cell migration was quantified using transwell migration and wound healing assays. Protein expression was assessed using Western blot analysis. Small interfering RNA was used to interfer protein expression. Immunoprecipitation was performed to detect the protein-protein interactions. Results: Tangeretin decreased cell proliferation and increased G2/M arrest. Tangeretin decreased cell migration. Tangeretin increased the LC3II/LC3I ratio and decreased p62 expression in HepG2 cells. Furthermore, the knockdown of BECLIN1 expression in HepG2 cells partially converted the Tangeretin-induced inhibition of proliferation, migration and autophagy. In addition, Tangeretin activated the JNK1/Bcl-2 pathway and disturbed the interaction between Bcl-2 and BECLIN1. Together, our findings demonstrate that Tangeretin inhibited the proliferation and migration of HepG2 cells through JNK/Bcl-2/BECLIN1 pathway-mediated autophagy. Conclusion: Our study contributes to the understanding of the inhibitory mechanism of Tangeretin on HCC development.

Tangeretin promotes regulatory T cell differentiation by inhibiting Notch1/Jagged1 signaling in allergic rhinitis

BACKGROUND AND OBJECTIVE

Tangeretin demonstrates broad anti-inflammatory effects. The present study aimed to assess whether tangeretin functions in regulating T-regulatory cells (Tregs) and alleviating allergic rhinitis (AR).

METHODS

An ovalbumin (OVA)-induced AR animal model was constructed to monitor the changes in the allergic symptom score, OVA-specific IgE titers, histopathological characteristics and T-helper cell (Th1, Th2, and Th17)-related cytokine levels under tangeretin or dexamethasone (DXM) administration. The expression levels of Notch1/Jagged1 and FOXP3, and the proportion of Tregs in the spleens of these animals, were also detected. Furthermore, purified naive CD4 + T cells were utilized to assess the effects of tangeretin on Notch1 expression and their differentiation in vitro.

RESULTS

Both tangeretin and DXM administration alleviated airway inflammation, decreased the production of serum OVA-induced IgE, but only tangeretin administration restored the balance of cytokine profiles compared with those in the AR group. The abundance of splenic CD4 + CD25 + FOXP3 + Treg cells and the transcription factor FOXP3 were significantly increased under tangeretin treatment, either in AR mice or in naïve CD4 + T-cell differentiation, followed by a concomitant reduction in Notch1/Jagged1 expression. However, as a positive control, the treatment of allergic rhinitis with dexamethasone was not related to the expression of Notch1/Jagged1 or the differentiation of Treg cells.

CONCLUSION

Tangeretin could promote regulatory T cell responses by inhibiting Notch1/Jagged1 expression, followed by promoting FOXP3/Treg cell differentiation and thus could serve as a novel curative therapeutic for AR.

Tangeretin protects human brain microvascular endothelial cells against oxygen-glucose deprivation-induced injury

Tangeretin, a citrus flavonoid extracted from the peel of citrus fruits, was reported to possess antiasthmatic, antioxidant, anti-inflammatory, and neuroprotective properties. However, the effect of tangeretin on human brain microvascular endothelial cells (HBMECs) has not been examined. This study was designed to investigate the protective effects of tangeretin on oxygen-glucose deprivation (OGD)-induced injury of HBMECs, and explore the underlying mechanisms. Our results showed that tangeretin improved HBMECs viability in response to OGD. In addition, tangeretin was able to increase the activity of superoxide dismutase and decrease the levels of reactive oxygen species and malondialdehyde (MDA), as well as ameliorate cell apoptosis in OGD-stimulated HBMECs. Mechanistic studies showed that tangeretin prevented the activation of JNK signaling pathway in OGD-stimulated HBMECs. Taken together, our current study demonstrated that tangeretin could ameliorate OGD-induced HBMECs injury through the JNK signaling pathway. Thus, tangeretin might be used as a therapeutic strategy for ischemia-reperfusion brain injury and related diseases.

Tangeretin inhibits streptozotocin-induced cell apoptosis via regulating NF-κB pathway in INS-1 cells

Oxidative stress is considered to play an important role in inducing the pancreatic β-cells apoptosis and promoting the development of diabetes mellitus. Tangeretin is a plant-derived flavonoid that retains antidiabetic effects. However, the role of tangeretin in streptozotocin (STZ)-induced β-cell apoptosis remains unclear. In this study, we aimed to examine the effects of tangeretin on STZ-induced cell apoptosis and the underlying mechanisms implicated in vitro. Our results showed that tangeretin improved the cell viability in STZ-induced INS-1 cells. Tangeretin reduced the increase of apoptosis ratio and revered the altered expressions of Bax and Bcl-2 caused by STZ induction. Furthermore, the impairment of insulin secretion ability as well as a reduction in messenger RNA levels of insulin 1 and 2 was significantly attenuated by tangeretin in STZ-induced INS-1 cells. Moreover, tangeretin resulted in a significant decrease in reactive oxygen species content, accompanied by an evident increase in the activities of superoxide dismutase, catalase, and glutathione peroxidase. Mechanistic studies further revealed that tangeretin inhibited the NF-κB pathway in STZ-induced INS-1 cells. These data indicated that tangeretin improved the cell apoptosis induced by STZ in INS-1 cells, which might be partly due to its antioxidant potential. Furthermore, NF-κB was found to be involved in the protective effect of tangeretin. Collectively, the results indicated that tangeretin could be used as a therapeutic approach for diabetes mellitus treatment.

Determination of Tangeretin in Rat Plasma: Assessment of Its Clearance and Absolute Oral Bioavailability

Tangeretin (TAN) is a dietary polymethoxylated flavone that possesses a broad scope of pharmacological activities. A simple high-performance liquid chromatography (HPLC) method was developed and validated in this study to quantify TAN in plasma of Sprague-Dawley rats. The lower limit of quantification (LLOQ) was 15 ng/mL; the intra- and inter-day assay variations expressed in the form of relative standard deviation (RSD) were all less than 10%; and the assay accuracy was within 100 ± 15%. Subsequently, pharmacokinetic profiles of TAN were explored and established. Upon single intravenous administration (10 mg/kg), TAN had rapid clearance (Cl = 94.1 ± 20.2 mL/min/kg) and moderate terminal elimination half-life (t_{1/2 λz} = 166 ± 42 min). When TAN was given as a suspension (50 mg/kg), poor but erratic absolute oral bioavailability (mean value < 3.05%) was observed; however, when TAN was given in a solution prepared with randomly methylated-β-cyclodextrin (50 mg/kg), its plasma exposure was at least doubled (mean bioavailability: 6.02%). It was obvious that aqueous solubility hindered the oral absorption of TAN and acted as a barrier to its oral bioavailability. This study will facilitate further investigations on the medicinal potentials of TAN.